/*******************************************************************************
 * This file is part of blueprint4j www.blueprint4j.org.
 * 
 *     blueprint4j is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU Lesser General Public License as published by
 *     the Free Software Foundation, either version 3 of the License, or
 *     (at your option) any later version.
 * 
 *     blueprint4j is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU Lesser General Public License for more details.
 * 
 *     You should have received a copy of the GNU Lesser General Public License
 *     along with blueprint4j. If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
//////////////////////license & copyright header/////////////////////////
//                                                                     //
//    Base64 - encode/decode data using the Base64 encoding scheme     //
//                                                                     //
//                Copyright (c) 1998 by Kevin Kelley                   //
//                                                                     //
// This library is free software; you can redistribute it and/or       //
// modify it under the terms of the GNU Lesser General Public          //
// License as published by the Free Software Foundation; either        //
// version 2.1 of the License, or (at your option) any later version.  //
//                                                                     //
// This library is distributed in the hope that it will be useful,     //
// but WITHOUT ANY WARRANTY; without even the implied warranty of      //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the       //
// GNU Lesser General Public License for more details.                 //
//                                                                     //
// You should have received a copy of the GNU Lesser General Public    //
// License along with this library; if not, write to the Free Software //
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA           //
// 02111-1307, USA, or contact the author:                             //
//                                                                     //
// Kevin Kelley <kelley@ruralnet.net> - 30718 Rd. 28, La Junta, CO,    //
// 81050  USA.                                                         //
//                                                                     //
////////////////////end license & copyright header///////////////////////

package blueprint4j.utils;
import java.io.*;       // needed only for main() method.
import java.util.ArrayList;
import java.util.List;


/**
*   Provides encoding of raw bytes to base64-encoded characters, and
*  decoding of base64 characters to raw bytes.
*
* @author Kevin Kelley (kelley@ruralnet.net)
* @version 1.3
* @date 06 August 1998
* @modified 14 February 2000
* @modified 22 September 2000
*/
public class Base64 {

	/**
	* returns an array of base64-encoded characters to represent the
	* passed data array.
	*
	* @param data the array of bytes to encode
	* @return base64-coded character array.
	*/
	static public char[] encode(byte[] data)
	{
		char[] out = new char[((data.length + 2) / 3) * 4];

		//
		// 3 bytes encode to 4 chars.  Output is always an even
		// multiple of 4 characters.
		//
		for (int i=0, index=0; i<data.length; i+=3, index+=4) {
			boolean quad = false;
			boolean trip = false;

			int val = (0xFF & (int) data[i]);
			val <<= 8;
			if ((i+1) < data.length) {
				val |= (0xFF & (int) data[i+1]);
				trip = true;
			}
			val <<= 8;
			if ((i+2) < data.length) {
				val |= (0xFF & (int) data[i+2]);
				quad = true;
			}
			out[index+3] = alphabet[(quad? (val & 0x3F): 64)];
			val >>= 6;
			out[index+2] = alphabet[(trip? (val & 0x3F): 64)];
			val >>= 6;
			out[index+1] = alphabet[val & 0x3F];
			val >>= 6;
			out[index+0] = alphabet[val & 0x3F];
		}
		return out;
	}
	
	/**
	 * Decodes a BASE-64 encoded stream to recover the original
	 * data. White space before and after will be trimmed away,
	 * but no other manipulation of the input will be performed.
	 *
	 * As of version 1.2 this method will properly handle input
	 * containing junk characters (newlines and the like) rather
	 * than throwing an error. It does this by pre-parsing the
	 * input and generating from that a count of VALID input
	 * characters.
	 **/
	public static byte[] decode(String sdata)
	{
		char data[] = sdata.toCharArray(); 
		// as our input could contain non-BASE64 data (newlines,
		// whitespace of any sort, whatever) we must first adjust
		// our count of USABLE data so that...
		// (a) we don't misallocate the output array, and
		// (b) think that we miscalculated our data length
		//     just because of extraneous throw-away junk
		int tempLen = data.length;
		for( int ix=0; ix<data.length; ix++ )
		{
			if( (data[ix] > 255) || codes[ data[ix] ] < 0 )
				--tempLen;  // ignore non-valid chars and padding
		}
		// calculate required length:
		//  -- 3 bytes for every 4 valid base64 chars
		//  -- plus 2 bytes if there are 3 extra base64 chars,
		//     or plus 1 byte if there are 2 extra.

		int len = (tempLen / 4) * 3;
		if ((tempLen % 4) == 3) len += 2;
		if ((tempLen % 4) == 2) len += 1;

		byte[] out = new byte[len];



		int shift = 0;   // # of excess bits stored in accum
		int accum = 0;   // excess bits
		int index = 0;

		// we now go through the entire array (NOT using the 'tempLen' value)
		for (int ix=0; ix<data.length; ix++)
		{
			int value = (data[ix]>255)? -1: codes[ data[ix] ];

			if ( value >= 0 )           // skip over non-code
			{
				accum <<= 6;            // bits shift up by 6 each time thru
				shift += 6;             // loop, with new bits being put in
				accum |= value;         // at the bottom.
				if ( shift >= 8 )       // whenever there are 8 or more shifted in,
				{
					shift -= 8;         // write them out (from the top, leaving any
					out[index++] =      // excess at the bottom for next iteration.
					   (byte) ((accum >> shift) & 0xff);
				}
			}
			// we will also have skipped processing a padding null byte ('=') here;
			// these are used ONLY for padding to an even length and do not legally
			// occur as encoded data. for this reason we can ignore the fact that
			// no index++ operation occurs in that special case: the out[] array is
			// initialized to all-zero bytes to start with and that works to our
			// advantage in this combination.
		}

		// if there is STILL something wrong we just have to throw up now!
		if( index != out.length)
		{
			throw new Error("Miscalculated data length (wrote " + index + " instead of " + out.length + ")");
		}

		return out;
	}
	
	public static byte[] decode(char data[]) {
		String sdata = new String(data);
		sdata = Utils.replaceAll(sdata,"==","#");
		sdata = Utils.replaceAll(sdata,"=","$");
		sdata = Utils.replaceAll(sdata,"#","$");
		VectorString vs = new VectorString(sdata,"$");
		byte bytes[] = new byte[0];
		for (int i = 0;i < vs.size() && vs.get(i) != null;i++) {
			bytes = ByteM.concat(bytes,decode(vs.get(i)));
		}
		return bytes;
	}


	//
	// code characters for values 0..63
	//
	static private char[] alphabet =
	   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
	   .toCharArray();

	//
	// lookup table for converting base64 characters to value in range 0..63
	//
	static private byte[] codes = new byte[256];
	static {
		for (int i=0; i<256; i++) codes[i] = -1;
		for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte)(     i - 'A');
		for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte)(26 + i - 'a');
		for (int i = '0'; i <= '9'; i++) codes[i] = (byte)(52 + i - '0');
		codes['+'] = 62;
		codes['/'] = 63;
	}




	///////////////////////////////////////////////////
	// remainder (main method and helper functions) is
	// for testing purposes only, feel free to clip it.
	///////////////////////////////////////////////////

	public static void main(String[] args)
	{
		byte dec[] = decode(new String(encode(new byte[]{-112})).toCharArray());
		if (true) return;
		boolean decode = false;

		if (args.length == 0) {
			Log.info.out("usage:  java Base64 [-d[ecode]] filename");
			System.exit(0);
		}
		for (int i=0; i<args.length; i++) {
			if ("-decode".equalsIgnoreCase(args[i])) decode = true;
			else if ("-d".equalsIgnoreCase(args[i])) decode = true;
		}

		String filename = args[args.length-1];
		File file = new File(filename);
		if (!file.exists()) {
			Log.info.out("Error:  file '" + filename + "' doesn't exist!");
			System.exit(0);
		}

		if (decode)
		{
			char[] encoded = readChars(file);
			byte[] decoded = decode(encoded);
			writeBytes(file, decoded);
		}
		else
		{
			byte[] decoded = readBytes(file);
			char[] encoded = encode(decoded);
			writeChars(file, encoded);
		}
	}

	private static byte[] readBytes(File file)
	{
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		try
		{
			InputStream fis = new FileInputStream(file);
			InputStream is = new BufferedInputStream(fis);
			int count = 0;
			byte[] buf = new byte[16384];
			while ((count=is.read(buf)) != -1) {
				if (count > 0) baos.write(buf, 0, count);
			}
			is.close();
		}
	catch (Exception e) { e.printStackTrace(); }

		return baos.toByteArray();
	}

	private static char[] readChars(File file)
	{
		CharArrayWriter caw = new CharArrayWriter();
		try
		{
			Reader fr = new FileReader(file);
			Reader in = new BufferedReader(fr);
			int count = 0;
			char[] buf = new char[16384];
			while ((count=in.read(buf)) != -1) {
				if (count > 0) caw.write(buf, 0, count);
			}
			in.close();
		}
	catch (Exception e) { e.printStackTrace(); }

		return caw.toCharArray();
	}

	private static void writeBytes(File file, byte[] data) {
		try {
			OutputStream fos = new FileOutputStream(file);
			OutputStream os = new BufferedOutputStream(fos);
			os.write(data);
			os.close();
		}
		catch (Exception e) { e.printStackTrace(); }
	}

	private static void writeChars(File file, char[] data) {
		try {
			Writer fos = new FileWriter(file);
			Writer os = new BufferedWriter(fos);
			os.write(data);
			os.close();
		}
		catch (Exception e) { e.printStackTrace(); }
	}
	///////////////////////////////////////////////////
	// end of test code.
	///////////////////////////////////////////////////
	
}
